1. Field of the Invention
The present invention refers to an aerial-supported procedure for the detection of landmines, duds or similar explosive bodies using a fluorescence procedure, including aerial-supported geo-referencing of the detected locations by means of a digital terrain model.
2. Description of Related Art
Areas strewn with landmines represent a considerable danger for the civilian population. This correspondingly applies also for areas where there are so-called duds, i.e. shells, bombs and other explosive bodies that have not been made to detonate. In addition, the latter represent a considerable danger because the ignition mechanism can be triggered off through external actions as driving or walking over the respective area. Whenever the term “mines” is used hereafter, it includes all explosive bodies existing in an area.
Areas strewn with mines constitute a considerable risk for the civilian population even decades after the ending of hostilities or after their laying. Thus for example, minefields that were laid during the Second World War are not usable up to the present day in parts of Europe and Africa. The same applies for areas suspected of containing mines where it is not clear whether there were mines laid there or not, and which are correspondingly made inaccessible for security reasons. In addition to the direct danger to people, there are also considerable economic disadvantages caused by the non-usability of the affected areas, especially for agriculture or transport.
A well-known procedure for clearing minefield is the use of sniffer dogs which trace olfactively mines laid in the earth. The locations of the mines indicated by the sniffer dog are then checked by a diffusing expert and the mine, if present, diffused. However, considerable disadvantages are evident with this procedure. The reliability of the indication by the sniffer dogs is very limited and is subject to a high error rate. Especially problematic here is that a considerable number of mines are not indicated by the sniffer dogs. Thus it is normal that an area to be cleared is gone over at least three times by different sniffer dogs. This type of negative error, i.e. a non-indication of mine location, is extremely dangerous for both the dog and dog-handler since the non-indicated mine can be inadvertently stepped on and triggered off. Moreover, the effective time of use for mine sniffer dogs is limited to a few hours per day. Beyond this time, the efficiency of the sniffer dogs lessens to a degree that is not defensible.
Further established methods are the bit-by-bit digging by hand of the terrain, the scanning of the area being examined with metal detectors or the mechanical setting-off of mines by means of rollers or by devices that plough up the earth. All these devices have, however, their specific disadvantages. Metal detectors are not designed to deal with plastic mines, which are especially used as mines targeting people, and so bring the user into danger. Rollers or devices that plough up the earth are usable only restrictively dependent on the suitability of the terrain. Moreover, the danger exists that mines, especially those targeting vehicles, which are constructed for to be driven over several times before exploding are thereby not triggered off and thus made harmless.
The publication GB 2 330 801 describes an aerial-supported system for the clearance of mines whereby the area to be cleared is illuminated by a laser. A sensor registers a different reflection behaviour of the landmine or the soil above the landmine in contrast to the surroundings. The so-detected location of the mine can be marked via a colour cannon or the mine can be made to explode from the air.
U.S. Pat. No. 5,972,638 describes a procedure for detecting buried or submerged explosive bodies by means of a biosensor. By biosensors are here meant micro-organisms that, due to manipulation, especially by genetic engineering, are enabled to become luminescent, especially fluorescent, in the presence of explosives. The document describes especially the use of recombinant bacterial strains of the bacillus groups, pseudomonas, as well as Escherichia Coli as biosensors and also procedures for the genetic engineering of these. The biosensors named exhibit luminescence, respectively fluorescence behaviour in the presence of explosives, especially trinitrotoluol, hexahydro-1,3,5-trinitro-1,3,5-triazine as well as octahydro-1,3,5-trinitro-1,3,5,7-tetrazocine. Further, other biosensors for determining explosives are also known from the publications DE 41 26 692, WO 02/068473, WO 97/03201. The publication WO 99/34212 describes also the manufacturing process and the use of fluorescent biosensors that are suitable for detecting explosives.
In order to carry out the procedure for detecting buried explosive bodies, a solution containing the biosensor is sprayed over the area under examination, preferably from an aeroplane, followed by a sufficient time for the micro-organisms to become effective in the area under examination.
The detection is effected by means of a CCD camera during twilight. Hereby, the vicinity of the camera is alternately radiated with UV light. The camera system takes shots under UV radiation and also without using it, by which, depending on the corresponding image processing, the respective positions of the explosive bodies become recognisable by the UV fluorescence.
The fluorescent lamps and the camera system can be carried by the user. Alternatively, the installation on a robot is possible. The system has the disadvantage that the minefield or the suspected area has to be walked on or driven over and only small areas can be checked in one working step due to the limited range. Moreover, the daily work slot is confined to a few hours at twilight, both at the start and the end of the day.
Furthermore, there is the added problem that many of the areas strewn with mines are in countries with low economic power, especially in Africa and South-East Asia. These countries can raise only small amounts of financial resources, or none at all, for the clearing of minefields. Therefore there is an urgent need to provide an efficient, safe and cost-effective procedure for the detection and clearance of minefields and the like.